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Role of non-homologous end-joining in T-DNA integration in Arabidopsis thaliana

Promotor: P. J. J. Hooykaas Co-promotor: B. S de Pater

Hexi Shen
19 januari 2017
Thesis in Leiden Repository

Double-strand breaks (DSBs) are one of the most lethal forms of DNA damage. To prevent this, cells have evolved complex and highly conserved systems to detect these lesions, signal their presence, trigger various downstream events and finally bring about repair. Two main pathways are used for DNA DSB repair: Homologous Recombination (HR) and Non-Homologous End-Joining (NHEJ). Both of them function together to maintain genome integrity. At least two NHEJ pathways have been identified: the classic NHEJ pathway (c-NHEJ) and the backup-NHEJ pathway (b-NHEJ) also called alternative-NHEJ (a-NHEJ) or microhomology-mediated end-joining (MMEJ). Agrobacterium tumefaciens is widely used as a vector to produce genetically modified plants. Agrobacterium-mediated genetic transformation involves the transfer of T-DNA from its tumor-inducing plasmid to the host cell nucleus, where it integrates into the plant genome. However, the molecular mechanism of T-DNA integration is still unclear. T-DNAs can integrate at artificially induced DSBs, which suggests that DSB repair mechanisms are probably involved in T-DNA integration in plants. Arabidopsis NHEJ mutants have subsequently been studied for T-DNA integration. However, the results obtained by different research groups were variable and revealed either no or limited negative effects.